CN104745075B - Inorganic passivation coating material, method for forming the same, and inorganic passivation protective film formed thereby - Google Patents

Abstract

The present disclosure provides a method for forming an inorganic passivation coating, comprising: mixing 5 to 80 parts by weight of tetraalkoxysilane, 10 to 80 parts by weight of trialkoxysilane, and 1 to 30 parts by weight of a catalyst, reacting at a pH value between 0.05 and 4 to form an inorganic resin material; and modifying the inorganic resin material with a phosphate ester to form an inorganic passivation coating, wherein the amount of the phosphate ester added is 0.1 to 10 parts by weight, based on 100 parts by weight of the inorganic resin material. The present disclosure also provides an inorganic passivation coating, and an inorganic passivation protective film formed therefrom.

Description

Inorganic passivation coating, its forming method, and formed inorganic passivation protective film

technical field

The present disclosure relates to an inorganic passivation coating and a forming method thereof, and an inorganic passivation protection film formed from the inorganic passivation coating, and in particular to an inorganic passivation protection film for metal surface treatment.

Background technique

Hexavalent chromium has long been used as a passivation film on the surface of galvanized steel sheets or aluminum alloys. Equipment Directive (Waste Electronics and Electrical Equipment; WEEE)" and other EU environmental protection directives came into force, and countries such as the United States, China, and Japan also began to restrict the use of hexavalent chromium after 2006. At present, the common alternative is to use organic resins to mix inorganic materials. Due to the need to rely on a large amount of organic resins to maintain good film-forming properties, the weather resistance and heat resistance are insufficient.

In addition to corrosion protection, the passivation film also needs to have sufficient electrical conductivity and heat resistance. At present, a large number of electronic products use galvanized steel as the casing material, such as refrigerators, ovens, computer hosts and washing machines, etc. The demand for environmental protection passivation treatment is imminent.

Contents of the invention

One of the purposes of the present invention is to provide a method for forming an inorganic passivation coating, so that the formed inorganic passivation protective film has characteristics that cannot be achieved by the prior art, such as good corrosion resistance, good heat resistance, and high hardness. .

Another object of the present invention is to provide the inorganic passivation coating formed by the above method.

Another object of the present invention is to provide an inorganic passivation protective film coated and cured by the above-mentioned inorganic passivation coating.

According to an embodiment, the present disclosure provides a method for forming an inorganic passivation coating, comprising: mixing about 5-80 parts by weight of tetraalkoxysilane (tetraalkoxysilane), about 10-80 parts by weight of trialkoxysilane ( trialkoxysilane), and about 1 to 30 parts by weight of a catalyst, react at a pH of about 0.05 to 4 to form an inorganic resin material; and modify the inorganic resin material with phosphate to form an inorganic resin In the passive coating, the amount of phosphoric acid ester added is about 0.1-10 parts by weight, based on 100 parts by weight of inorganic resin material.

According to another embodiment, the present disclosure provides an inorganic passivation coating formed by the aforementioned method, wherein the inorganic content of the inorganic passivation coating is at least about 50 wt%.

According to yet another embodiment, the present disclosure provides an inorganic passivation protective film, which is formed by coating and curing the aforementioned inorganic passivation coating, wherein the film thickness of the inorganic passivation protective film is greater than 0 μm and less than or equal to about 20 μm , and the surface hardness of the inorganic passivation protective film is at least about 2H.

The advantages of the present invention are: in the inorganic passivation coating provided by the present invention, there is no need to add additional organic macromolecules, only the sol-gel reaction is carried out by trialkoxysilane, tetraalkoxysilane and catalyst, and Through the ratio of tetraalkoxysilane and trialkoxysilane and the pH value of the reaction, the degree of molecular linearity and network crosslinking is controlled, and an inorganic resin material with a partly linear and partly network structure is synthesized. The inorganic passivation protective film formed has the advantages of good corrosion resistance (salt spray resistance ≥ 72 hours), good heat resistance (the appearance does not change after 500 ° C heat treatment for 1 minute), high hardness (above 2H), etc. In addition, the present invention modifies the inorganic resin material by utilizing phosphoric acid ester, and then solidifies and forms a film, and the formed inorganic passivation protective film has high corrosion resistance (salt spray resistance ≥ 400 hours), does not contain heavy metals (such as Hexavalent chromium), good adhesion and compactness, etc.

In order to make the above and other purposes, features, and advantages of the present disclosure more comprehensible, preferred embodiments are specifically listed below, together with the accompanying drawings, and described in detail as follows:

Description of drawings

FIG. 1 shows a method for forming an inorganic passivation coating according to an embodiment of the present disclosure;

Fig. 2 shows the formed inorganic passivation protection film in an embodiment;

Among them, the symbol description:

102, 104～steps; 200～substrate;

202～Inorganic passivation protective film.

detailed description

Several different embodiments are listed below according to different features of the present disclosure. The specific components and arrangements in the present disclosure are for simplicity, but the present disclosure is not limited to these embodiments. For example, a description of forming a first component over a second component may include embodiments in which the first component is in direct contact with the second component, as well as having an additional component formed between the first component and the second component such that the second component An embodiment in which one component is not in direct contact with a second component. In addition, for the sake of brevity, the present disclosure is represented by repeated component symbols and/or letters in different examples, but this does not mean that there is a specific relationship between the various embodiments and/or structures.

In an embodiment of the present disclosure, a method for forming an inorganic passivation coating is provided, including reacting with a trialkoxysilane, a tetraalkoxysilane, and a catalyst (such as a sol-gel (sol-gel) reaction), And through the ratio of tetraalkoxysilane and trialkoxysilane and the pH value of the reaction, the degree of molecular linearity and network crosslinking is controlled to synthesize an inorganic resin material with both partial linear and partial network structures.

FIG. 1 illustrates a method for forming an inorganic passivation coating according to an embodiment of the present disclosure. Referring to FIG. 1 , in step 102, tetraalkoxysilane, trialkoxysilane, and a catalyst are mixed and reacted (taking sol-gel reaction as an example) to form an inorganic resin material. In step 104, the inorganic resin material formed in step 102 is chemically modified by adding phosphate ester, wherein the phosphate ester can be used as a surface passivation agent to form an inorganic passivation coating.

In this sol-gel (sol-gel) reaction, the tetraalkoxysilane can have the following chemical formula:

Wherein, each R ₁ is independently a C ₁ -C ₈ linear alkyl group.

Furthermore, trialkoxysilanes have the following chemical formula:

Wherein, each R ₂ is independently C ₁ -C ₈ linear alkyl; R ₃ is hydrogen, substituted or unsubstituted C ₁ -C ₈ alkyl, substituted or unsubstituted C ₁ -C ₈ alkenyl , epoxy, or amino. In one embodiment, the substituent of R ₃ is, for example, fluorine.

Table 1 and Table 2 show examples of tetraalkoxysilanes and trialkoxysilanes in some embodiments of the present disclosure. It should be noted that these examples are for illustration only, and the scope of the present disclosure is not limited thereto.

Table 1

Table 2

In addition, in step 102 of Figure 1, the catalyst used in the sol-gel (sol-gel) reaction, for example, includes hydrochloric acid, nitric acid, acetic acid, sulfuric acid, or a combination of the foregoing, by which the sol can be made - The sol-gel reaction is carried out under acidic conditions with a pH value ranging from 0.05 to 4, for example: a pH value ranging from 1 to 3. The inorganic passivation coating formed by the inorganic resin material obtained in this acidic environment has good hardness and adhesion, and it is inferred that this should be related to the inorganic resin material which is easy to form a linear structure in an acidic environment.

It should be noted that if the above sol-gel reaction is carried out under alkaline conditions, the reactants may undergo polymerization and hydrolysis at the same time to form products with similar spherical structures. Under alkaline conditions, the polymerization rate is faster and the hydrolysis rate is slower, so the reaction tends to form a core (core) that develops in a four-dimensional direction, thus forming a spherical structure. Although this spherical structure can have the effect similar to powder stacking to achieve thick coating when coating and forming a film, the hardness and adhesion are not good (the hardness is less than H, and it cannot pass the 100/100 hundred grid test).

On the contrary, under acidic conditions, due to the slower polymerization rate and faster hydrolysis rate, the reaction tends to form a linear (linear) core (core) first, and then extend outward, so it can form a partially linear part and a part mesh structure. The coating film formed by this product is suitable for a wide range of applications because its linear part can prevent cracking, and the network structure can improve density and corrosion resistance.

In the present disclosure, the proportions of the components in this sol-gel reaction can be adjusted as needed to obtain an inorganic resin material with desired properties. For example, in this sol-gel (sol-gel) reaction, 5-80 parts by weight of tetraalkoxysilane, 10-80 parts by weight of trialkoxysilane, and 1-30 parts by weight of catalyst may be included. . In another embodiment, the sol-gel (sol-gel) reaction may include 5-50 parts by weight of tetraalkoxysilane, 10-50 parts by weight of trialkoxysilane, and 1-15 parts by weight of catalyst. Experiments have found that the higher the content of tetraalkoxysilane, the higher the crosslinking density of the formed inorganic resin material, and the hardness and corrosion resistance of the formed coating film are also increased, but it is also easier to be brittle, so Appropriate addition of trialkoxysilane is needed for modification. In addition, if there is too much trialkoxysilane, the formed inorganic resin material has low chemical crosslinking density, and the physical properties of the formed coating film are poor, and even cannot be hardened to form a film. Therefore, the appropriate proportion of ingredients can be adjusted according to the desired hardness. In addition, the inorganic resin material formed in some embodiments of the present disclosure may have relatively high inorganic content, for example: more than 50wt%, for example: greater than or equal to 50wt%, less than or equal to 99wt%, good corrosion resistance and weather resistance .

The phosphate used in step 104 in FIG. 1 includes, for example: phosphate-based silane (phosphatosilane), phosphate-based titanium alkoxide (phosphato titanium alkoxide), thiol-based phosphate (sulfhydryl hydroxyl phosphate), or the aforementioned The combination. The amount of phosphoric acid ester added is about 0.1-10 parts by weight or about 1-8 parts by weight, based on 100 parts by weight of the inorganic resin material. By means of the siloxane group, titanyl group or mercaptan group contained in the above-mentioned phosphate ester, the silanol group or silane group at the end of the inorganic resin is chemically modified, in addition to making the formed inorganic passivation coating In addition to good heat resistance and corrosion resistance, because the inorganic resin material itself has a high inorganic content, the formed inorganic passivation coating also has good weather resistance and heat resistance. It should be noted that the surface passivation agent used in the inorganic passivation coating provided by the present disclosure does not include heavy metal salts, such as chromate, molybdate, vanadate or phosphate, that is, does not include hexavalent chromium. In one embodiment, the hexavalent chromium content of the formed inorganic passivation coating is ≤1 mg/kg, such as ≤0.1 mg/kg.

The above-mentioned phosphate ester silane (phosphatosilane) includes, for example Wherein each R ₃ is independently hydrogen, methyl, ethyl, propyl, or butyl, etc.

The above-mentioned phosphate ester titanium alkoxide (phosphato titanium alkoxide) for example includes: Wherein each R is independently hydrogen, methyl, ethyl, propyl, butyl, or isopropyl and the like.

The above-mentioned thiol-based phosphate (sulfhydryl hydrocarbyl phosphate) includes, for example:

In one embodiment, in step 104 shown in FIG. 1 , the modifying with phosphate ester is carried out under an organic solvent. In one embodiment, about 0.01-80 parts by weight of an organic solvent, such as methanol, ethanol, isopropanol, butanol, sec-butanol, tert-butanol, or a combination thereof, may be added.

In addition, 0.0001 to 0.1 parts by weight of film-forming aids such as: etc., or paint additives such as: or Desmodur etc., to help increase the rate of the subsequent film-forming process and meet the requirements of the continuous process.

The inorganic passivation coating formed by the method of the present disclosure may have an inorganic content above 50wt% (residual ash content measured by thermogravimetric analyzer; TGA char yield), such as 50-80wt% or 50-90wt%. Wherein, the weight average molecular weight of the inorganic resin material is at least 1000 g/mol. In some embodiments of the present disclosure, the weight average molecular weight of the inorganic resin material is about 1000-10000 g/mol.

In addition, the above-mentioned inorganic passivation paint is coated and cured to form an inorganic passivation protective film, as shown in FIG. 2 . FIG. 2 shows a cross-sectional view of coating an inorganic passivation coating on a substrate 200 to form an inorganic passivation protection film 202 in one embodiment. The substrate 200 can be any solid substrate, such as a rigid substrate, including such as: metal, iron plate, steel plate, galvanized steel plate, aluminum alloy, magnesium alloy, lithium alloy, semiconductor, glass, ceramics, silicon substrate, or For example, flexible substrates, including: plastic substrates, such as PES (polyethersulfone), PEN (polyethylenenaphthalate), PE (polyethylene), PI (polyimide), PVC (polyvinyl chloride), PET (polyethyleneterephthalate), resin, or combination of the foregoing. The method of coating the inorganic passivation coating on the substrate 200 is, for example, spray coating, roll coating, dip coating, bar coating, spin coating ), knife coating, brush coating, or a combination of the foregoing. Then, the inorganic passivation coating is cured, and dried at 100-300° C., for example, 200° C., for 5-10 minutes to form an inorganic passivation protection film 202 with good surface hardness. In one embodiment, the surface hardness of the formed inorganic passivation protective film is at least 2H, even up to 4H.

It is worth mentioning that the passivation film generally used for surface treatment usually uses inorganic salts to oxidize the metal surface to form a chemical metal composite oxide film layer. Although the purpose of passivation and anti-corrosion can be achieved, the usual process is to use metal inorganic Salt treatment solution, such as: zinc phosphate, sodium nitrate or potassium dichromate and other acid treatment solutions, and dip coating is often used, so a large number of treatment solutions and soaking tanks are required, which not only increases the cost of acid sewage treatment in the factory area, but also affects the operation of acidic steam. hazard to personnel. In addition, due to the requirement of electrical conductivity, the thickness of the anti-corrosion film of such inorganic salts is less than 3 μm. Except for the hexavalent chromium film, the corrosion resistance of the rest is only 48-96 hours. However, the inorganic passivation protection film provided by the present disclosure is modified by phosphate, without adding inorganic acid salts, and its film thickness is less than or equal to 20 μm to meet the ideal corrosion resistance and surface conductivity requirements. In one embodiment, the thickness of the film is about 1-2 μm, for example, 1 μm, which meets the requirement that the surface conductivity of the steel plate used for electronic products is ≤ lmΩ/sq.

In addition, if the inorganic resin material (unmodified) of the present disclosure is simply coated and cured to form a film, its corrosion resistance is 72 hours. However, after modifying the inorganic resin material with phosphate ester, the formed inorganic passivation The protective film can form passivation protection such as good adhesion, heat resistance and corrosion resistance on the metal surface. After the neutral salt spray test, the generation time of 5% white rust on the surface is extended to more than 400 hours, and its corrosion resistance It can be increased by more than five times.

It should be noted that although organic polymers help to improve film-forming properties and flexibility, the weather resistance and surface hardness of organic-inorganic hybrid materials formed by them are insufficient. In contrast, in the inorganic passivation coating provided by the embodiments of the present disclosure, there is no need to add additional organic polymers (such as organic resins), and the sol-gel process is carried out by trialkoxysilane, tetraalkoxysilane, and catalysts. Gel (sol-gel) reaction, and through the ratio of tetraalkoxysilane and trialkoxysilane and the pH value of the reaction, the degree of linear and network crosslinking of the molecule is controlled, and the synthesis has both a partial linear and a partial network structure The inorganic resin material, with its high inorganic content, makes the formed inorganic passivation protective film have good corrosion resistance (salt spray resistance ≥ 72 hours), good heat resistance (the appearance does not change after 500 ° C heat treatment for 1 minute) , High hardness (above 2H) and so on. In addition, by modifying the inorganic resin material with phosphate ester, and then curing it to form a film, the formed inorganic passivation protective film has high corrosion resistance (salt spray resistance ≥ 400 hours), does not contain heavy metals (such as hexavalent chromium ), good adhesion and compactness.

Example 1

Mix tetraethoxysilane (TEOS), methyltriethylsilane (MTES), and epoxypropyltriethoxysilane (3-glycidoxypropyltrimethoxysilane; GPTMS) uniformly according to the ratio in Table 3, and stir at room temperature for 10 minutes Finally, water and 0.1N hydrochloric acid were added according to the ratio in Table 3, and then the sol-gel (sol-gel) reaction was carried out at room temperature for 16 hours, then the temperature was raised to 60°C, and the reaction was continued for 8 hours. An inorganic resin material with a partial network structure. Then add isopropyl alcohol (IPA), butyl phosphate titanoxane (Titanium, Bu phosphate Et alc.iso-Pr alc.Complexes; TBEP) (CAS NO.109037 -78-7) and uniformly mixed, stirred and reacted at room temperature for 16 hours, an inorganic passivation coating was formed.

Example 2

The manufacturing process is the same as in Example 1, except that butyl titanoxane phosphate (TBEP) is replaced by diethylphosphatoethyl triethoxysilane (PHS).

The inorganic passivation coating formed in Examples 1-2 was further heated up to 800-C with a thermal gravimetric analysis (TGA) to analyze the inorganic content (Char yield) of the inorganic passivation coating. In addition, film formation evaluation was performed. After drying for 5 minutes, drop a drop of water on the test piece, wipe it off after 1 minute, and observe whether there are traces. If there is no, it is ο, indicating that the coating can form a film and dry completely.

The inorganic passivation coatings of Examples 1-2 were coated with a rod (bar-coating) on a commercially available blank hot-dip galvanized steel sheet (Yehui Iron and Steel; Model SGC-CZSWX Z-12), and dried at 200°C for 5 Minutes to form an inorganic passivation protective film. The salt spray test is carried out according to Taiwan Standard 3627 (CNS3627), and the time for 5% white rust on the surface in the salt spray test is calculated as the corrosion resistance test result. The hexavalent chromium was detected by the Taiwan Standard 15331 (CNS15331) reagent method, and its 100-grid strength and surface pencil hardness were tested by the Taiwan Standard 10757 (CNS10757). Heat treatment at 500°C for 1 minute to test the heat resistance, if there is no change in the appearance, it is ο. The results of the above tests are shown in Table 4.

With reference to Table 4, in Examples 1-2, tetraethoxysilane, methyltriethylsilane, epoxypropyltriethoxysilane and hydrochloric acid were mixed according to the ratio of Table 3, and the formed inorganic passivation coating It has an inorganic content greater than 50% and a hardness of 4H, and can be formed into a film. Through the salt spray test, the salt spray resistance of the inorganic passivation protective film formed in embodiment 1 can reach 412 hours, and the salt spray resistance of the inorganic passivation protective film formed in embodiment 2 also reaches 288 hours, and both pass through There was no change in appearance after the heat resistance test. In addition, the tests of hexavalent chromium in Examples 1 and 2 were all negative reactions, showing that the hexavalent chromium content of the coating film was less than or equal to 1 mg/kg, which met RoHS environmental protection requirements (hexavalent chromium content was less than 1000 mg/kg), and the pencil hardness was 4H. .

Comparative example 1

Mix tetraethoxysilane, methyltriethylsilane) and epoxypropyltriethoxysilane according to the ratio in Table 3. After stirring for 10 minutes at room temperature, add water and 0.1N hydrochloric acid according to the ratio in Table 3. Add in a ratio of 3, then carry out the sol-gel reaction at room temperature for 16 hours, then raise the temperature to 60°C, and continue the reaction for 8 hours to obtain an inorganic resin material with a partially linear and partially network structure. Then add isopropanol (IPA) and zinc phosphate to the above inorganic resin material according to the ratio in Table 3 and mix evenly, and stir and react at room temperature for 16 hours. The addition of zinc phosphate results in incompatibility with other ingredients and precipitates which prevent further coating formation.

Comparative example 2-4

Comparative examples 2 to 4 are commercially available blank hot-dip galvanized steel sheets (Yehui Iron and Steel; model SG-CZSWX Z-12), commercially available organic anti-fingerprint hot-dip galvanized steel sheets (Yehui Iron and Steel; model YP Standard SGCD3-ZSEX Z08), and commercially available hexavalent chromium passivated hot-dip galvanized steel sheet (Yehui Iron and Steel; model ZN-Coating Mass Z-12). The salt spray test, hexavalent chromium test, hardness, heat resistance, and resistance value tests were carried out on comparative examples 2 to 4, and the results are shown in Table 4.

Referring to Table 4, the salt spray resistance of Comparative Example 2 (the commercially available blank hot-dip galvanized steel sheet) is less than 24 hours, the hardness is H, and oxidation blackening occurs after heat treatment at 500° C. for 1 minute. Comparative example 3 (commercially available organic anti-fingerprint hot-dip galvanized steel sheet) has a salt spray resistance of 120 hours, a hardness <H, and cracking and yellowing after heat treatment at 500° C. for 1 minute. Comparative example 4 (commercially available hexavalent chromium passivated hot-dip galvanized steel sheet) has a hardness of 4H and a salt spray resistance of 240 hours, but its hexavalent chromium test is positive.

table 3

*phr: based on 100 parts by weight of (TEOS+MTES+GPTMS+water+0.1N hydrochloric acid+isopropanol).

Table 4

The inorganic passivation coating provided by the present disclosure has a high inorganic content, so that the formed inorganic passivation protective film has good corrosion resistance (salt spray resistance ≥ 72 hours), good heat resistance (appearance after 500 ° C heat treatment for 1 minute) No change), high hardness (4H) and other advantages. In addition, by modifying the inorganic resin material with phosphate ester, and then curing it to form a film, the formed inorganic passivation protective film has high corrosion resistance (salt spray resistance ≥ 400 hours), does not contain heavy metals (such as hexavalent chromium ), good adhesion and compactness.

Although the present disclosure has been disclosed as above with several preferred embodiments, it is not intended to limit the present disclosure. Anyone with ordinary knowledge in the art can make arbitrary modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure should be determined by the scope defined by the appended claims.

Claims (13)

1. A method for forming an inorganic passivation coating, comprising: Mix 5-80 parts by weight of tetraalkoxysilane, 10-80 parts by weight of trialkoxysilane, and 1-30 parts by weight of catalyst, and react at a pH value of 0.05 to 4 to form an inorganic resin material; and Modifying the inorganic resin material with phosphoric acid ester to form an inorganic passivation coating, wherein the added amount of the phosphoric acid ester is 0.1-10 parts by weight, based on 100 parts by weight of the inorganic resin material; The phosphate ester is phosphate-based silane, titanyl phosphate-based titanoxane, thiol-based phosphate, or a combination thereof. 2. The method for forming an inorganic passivation coating according to claim 1, further comprising coating and curing the inorganic passivation coating to form an inorganic passivation protection film. 3. the formation method of inorganic passive coating as claimed in claim 1, wherein said tetraalkoxysilane has following chemical formula: Wherein, each R ₁ is independently a C ₁ -C ₈ linear alkyl group. 4. the formation method of inorganic passive coating as claimed in claim 1, wherein said trialkoxysilane has following chemical formula: Wherein, each R ₂ is independently C ₁ -C ₈ linear alkyl; R ₃ is hydrogen, substituted or unsubstituted C ₁ -C ₈ alkyl, substituted or unsubstituted C ₁ -C ₈ alkenyl , epoxy, or amino. 5. the formation method of inorganic passivation paint as claimed in claim 4, wherein _R For having the functional group that fluorine replaces. 6. the formation method of inorganic passivation coating as claimed in claim 1, wherein said phosphate-based silane is or wherein each R ₃ is independently hydrogen, methyl, ethyl, propyl, or butyl. 7. the formation method of inorganic passivation coating as claimed in claim 1, wherein said titanyl phosphate base titanoxane is wherein each R is independently hydrogen, methyl, ethyl, propyl, butyl, or isopropyl. 8. the formation method of inorganic passivation coating as claimed in claim 1, wherein said mercaptan phosphoric acid ester is or 9. The method for forming an inorganic passivation coating as claimed in claim 1, wherein the catalyst is hydrochloric acid, nitric acid, acetic acid, sulfuric acid, or a combination thereof. 10. An inorganic passivation coating formed by the forming method according to claim 1, wherein the inorganic content of the inorganic passivation coating is at least 50wt%. 11. The inorganic passivation coating of claim 10, wherein the weight average molecular weight of the inorganic resinous material is at least 1000. 12. The inorganic passivation coating according to claim 10, wherein the hexavalent chromium ion content of the inorganic passivation coating≦1mg/kg. 13. An inorganic passivation protective film is formed by coating and curing the inorganic passivation coating as claimed in claim 10, wherein the film thickness of the inorganic passivation protective film≦20 μm, and the surface hardness is at least for 2H.